The present invention concerns a so-called xe2x80x9chands-freexe2x80x9d access and/or engine starting system for automobile vehicles.
More particularly, the invention is a xe2x80x9chands-freexe2x80x9d access and/or engine starting system making use of an inside antenna.
In so-called xe2x80x9chands-freexe2x80x9d access systems for automobile vehicles, an identification or authentication device is installed on the vehicle to control the vehicle""s door locking means, this authentication device being able to interchange data over a certain distance with at least one identification device (hereinafter called an xe2x80x9cidentifierxe2x80x9d) carried by a user, to enable access to the vehicle when the identifier has been identified by the authentication device. To enable the dialog between the authentication device and the identifier and thereby detection of the presence of an identifier outside the vehicle, several antennas are generally mounted around the vehicle. Such antennas are fitted, for example, in rear-view mirrors, door handles, and door pillars. When the user locks the vehicle, for example by pressing on a specific button on the outside door handle, then moves away from the vehicle, the system assures automatic locking of the vehicle doors as soon as the identifier carried by the user exits the coverage zone of the outside antennas and become undetectable.
In addition, when a driver carrying an authorized identifier is inside the passenger compartment, such a system can also inhibit anti-starting devices, such as an electronic immobilizer, to enable starting of the vehicle""s engine. The authentication device can emit an identification signal via antennas mounted inside the vehicle to detect the identifier inside the vehicle. These antennas are fitted for example in the dashboard, seats or inside door panels.
However, a large number of antennas may be required, increasing material costs and vehicle assembly time.
Prior to hands-free external door locking, inside antennas can also be used to check for the presence of identifiers in the vehicle, to avoid locking a person or identifier in the car.
When the inside antennas are used for identification prior to engine starting, the identification signal emitted by the antennas must not propagate outside the vehicle, to ensure that the immobilization system is inhibited only if an authorized driver is in the car. This avoids the risk of accidental engine starting, for example when a child playing in the car operates the starter contactor while the driver carrying the identifier is standing outside the vehicle. To ensure that the detection zone does not extend beyond the passenger compartment, several antennas are necessary with deliberately restricted ranges to cover only the whole of the compartment.
The object of the invention it to overcome the disadvantages described previously and propose a xe2x80x9chands-freexe2x80x9d access system requiring fewer antennas, yet providing adequate coverage of the passenger compartment and the vehicle""s external environment.
For this purpose, the invention is an authentication device for automobile vehicles that controls door locking and/or engine starting and is able to interchange data over a certain distance with an identifier, intended to be carried by a user, when said identifier lies within the emission/reception coverage zone of said authentication device, to enable xe2x80x9chands-freexe2x80x9d vehicle access and/or engine starting when said identifier has been authenticated by said authentication device, wherein said authentication device is connected to a single antenna inside the vehicle passenger compartment and is able to emit via said antenna at least two distinct emission powers, a first emission power enabling said antenna to cover a first zone including at least part of said passenger compartment, and a second emission power greater than said first emission power enabling said antenna to cover a second zone including at least the whole of said passenger compartment and possibly a coverage zone outside said vehicle.
In a first embodiment of the invention, the authentication device emits via said antenna at a first emission power enabling the antenna to cover a first zone substantially limited to the inside of said passenger compartment, or at a second emission power greater than said first emission power enabling the antenna to cover a second zone extending beyond the first zone and including a coverage zone outside said vehicle to enable xe2x80x9chands-freexe2x80x9d access.
One particularity of the invention is that the authentication device is able to trigger, in response to user activation of an external system of the vehicle, an identification data interchange at said first emission power to detect the possible presence of an authorized identifier inside the vehicle, prior to authorizing vehicle door locking.
In a second embodiment, the authentication device emits via said antenna at a first emission power enabling the antenna to cover a first zone covering only part, preferably the major part, of said passenger compartment, or at a second emission power greater than said first emission power enabling the antenna to cover a second zone including the whole of said passenger compartment and a zone outside the vehicle and adjacent to it, without however extending over the whole of said coverage zone enabling xe2x80x9chands-freexe2x80x9d access.
In a variant of the second embodiment, the authentication device is able to emit via the inside antenna at three distinct emission powers, the third emission power being greater than said second emission power and enabling said antenna to cover a third zone which extends outside the vehicle and constitutes said coverage zone outside said vehicle enabling xe2x80x9chands-freexe2x80x9d access.
One particularity of the invention is that the authentication device is able to trigger, in response to user activation of an external system of the vehicle, an identification data interchange at said second emission power to detect the possible presence of an authorized identifier inside the vehicle, prior to authorizing vehicle door locking.
Another characteristic of the invention is that the authentication device is able to trigger, in response to user activation of an external system of the vehicle, an identification data interchange at an emission power sufficient to detect the possible presence of an authorized identifier in said coverage zone outside said vehicle enabling xe2x80x9chands-freexe2x80x9d access. Said external system is preferably the outside door handle or an outside contactor.
Advantageously, the location of the single antenna in said passenger compartment and the value of the emission power providing said coverage zone outside the vehicle are such that the antenna radiation is not blocked by metal barriers and/or vehicle door windows, but radiates outside said vehicle to cover said coverage zone.
Advantageously, the emission power assuring of said zone outside said vehicle to enable xe2x80x9chands-freexe2x80x9d access is such that the radiation reaches about 2 meters outside the vehicle.
Another characteristic of the invention is that the authentication device is able to trigger, in response to user activation of an engine starting contactor in said passenger compartment, an identification data interchange at said first emission power to detect the possible presence of an authorized identifier inside said passenger compartment, prior to permitting xe2x80x9chands-freexe2x80x9d engine starting.
The emission of the interrogation signal by the authentication device via the single antenna at the first emission power is preferably at low frequency, for example about 125 kHz.
The single antenna can take the form of a loop inside said passenger compartment.